It's funny, but I'm not sure it's what it looks like. The photographer is shooting with an autofocus telephoto lens, which extends for the shot. That suggests his subject is some distance away. Also, his line of sight appears to be slightly above and behind the volleyball girl who rolled onto her back.

My best guess? I think he's shooting the brown-haired girl in the back at the left, the one with the ponytail. After the flash fires, she looks looks at a friend, laughs, and gives a dismissive wave of the hand, as if her friend has just said, "Ooooh, you're a star now!"